Modularized B shaft turning and milling composite functional unit

The utility model discloses a modularized B shaft turning and milling composite functional unit and relates to a turning and milling composite functional unit for a numerical control machine. The modularized B shaft turning and milling composite functional unit comprises a B shaft module and a turning and milling head module. The B shaft module comprises a driving device, a three gear plate indexing structure and a brake structure; and the turning and milling head module comprises a motor driving device and a three gear plate fixing device. The turning and milling head module is driven by a built-in motor and is provided with a three gear plate locking structure. In the turning processing, three gear plates are locked so as to ensure the structural rigidity. In the milling or drilling process, the three gear plates are loosened and a spindle rotates to drive a tool to carry out machining. The B shaft module is driven by a built-in motor. In the indexing machining process, the three gear plate locking structur